As for materials for use in an electric or electronic field, as the speed of transmission signal increases, a low dielectric constant which decreases a time delay and a low dielectric loss tangent which decreases a loss are desired for utilizing a high-frequency wave (gigahertz band). Further, higher toughness is also desired in order to inhibit the occurrence of microcracks which are thought to be generated by thermal shock and secure high reliability. For the above demands, there are carried out attempts of incorporation of engineering plastic, such as polyphenylene ether (PPE), as a modified polymer having several properties. However, since a thermoplastic resin is directly incorporated into a thermosetting resin, problems remain with regard to the compatibility between the resins and molding processability.
For improving the compatibility, a method of improving compatibility by blending PPE with a different resin as a compatibilizing agent is discussed and the pseudo IPN structuralization of PPE and a cyanate resin is also discussed (JP-A-11-21452, etc.). However, the problems of molding processability and heat resistance have not been solved yet. Further, a method of converting a high molecular PPE into a low molecular compound is discussed for improving moldability. For example, there is known a method in which a high molecular PPE and polyphenols are redistributed in the presence of a radical catalyst (JP-A-9-291148, etc.). Further, for obtaining toughness, there is known a method in which a bivalent phenol and a monovalent phenol are subjected to oxidation polymerization to obtain a thermosetting resin having a cyanate ester group (JP-B-8-011747).
Concerning a semiconductor device, an epoxy resin composition is generally used for sealing electronic parts such as a semiconductor. The above-mentioned epoxy resin composition is composed of various epoxy resins such as a cresol novolak type epoxy resin, a bisphenol A type epoxy resin and a biphenyl type epoxy resin, a curing agent therefor, an inorganic filler, a curing accelerator as required, a coupling agent, a releasing agent, a coloring agent and the like.
In compliance with recent requirements for a decrease in size or a decrease in thickness, the formation technique of the above electronic parts is being changed from a conventional through hole mounting method (DIP: dual inline package, etc.) to a surface mounting method (SOP: small outline package, QFP: quad flat package, etc.). In the surface mounting method, since a semiconductor device is treated at a high temperature (for example 210° C.˜260° C.) at a solder reflow or the like at a mounting time, a high temperature heat is applied to the entire semiconductor device. In this case, problems such as the occurrence of cracks in a sealing layer formed of the above epoxy resin composition and a large decrease in humidity resistance are apt to occur.
Countermeasures against the above are proposed. One countermeasure with respect to handling is that a semiconductor device before mounting is packaged in a moisture-proof case. As an improvement in a sealing epoxy resin composition, for example, JP-A-1-108256 discloses a sealing material containing a biphenyl type epoxy resin and JP-A-64-24825 discloses a sealing material containing an epoxy resin and a polyphenylene ether type resin in combination.
However, these sealing materials have problems. For example, when a thin sealing layer having a thickness of 2.0 mm or less is used, cracks are apt to occur at the time of a solder reflow. In view of a further improvement in physical properties and an increase in a signal transmission speed in a chip circuit, it is demanded to carry out a sealing with a sealing layer having a lower dielectric constant.
With the advance of communication or computers, recently, higher frequency waves come to be used. Printed wiring boards are required to have low dielectric characteristics for the purpose of increasing a signal transmittal speed. For responding to the above demands, there are used thermoplastic resins such as a fluororesin excellent in dielectric characteristics or a general polyphenylene ether. However, these thermoplastic resins have problems about workability, moldability, heat resistance and the like. For example, the problems are that a solvent used for preparing a varnish is limited, and that due to a high melt viscosity, a high multilayer formation can not be carried out and a high temperature and a high pressure are required at a molding time
On the other hand, as a thermosetting resin, there are known a polyphenylene ether modified epoxy resin, a thermosetting type polyphenylene ether and the like. However, conventional thermosetting resins have the same problems as the above problems of the thermoplastic resins. Further, a cyanate ester resin is known as a thermosetting resin having excellent dielectric characteristic and excellent moldability. However, when a cyanate ester resin alone is used, a cured product is too hard and is fragile so that it has a problem about adhesive property and solder resistance. When a cyanate ester resin is used in combination with an epoxy resin, the above defects can be covered. However, it is difficult to cope with requirements of lower dielectric characteristics of laminates, which requirements are becoming severer, by using a conventional cyanate ester resin in combination with a conventional epoxy resin.
Epoxy (meth)acrylate compounds have been widely used as raw materials for various functional high molecular materials such as a photosensitive material, an optical material, a dental material, an electronic material and crosslinking agents for various polymers. However, since higher performances are required in these application fields in recent years, physical properties required as a functional high molecular material become severer increasingly. As such physical properties, for example, heat resistance, weather resistance, low moisture absorptivity, high refractive index, high fracture toughness, low dielectric constant and low dielectric loss tangent are required. Until now, these required physical properties have not been necessarily satisfied.
For example, concerning the production of a printed wiring board, it is known that epoxy (meth)acrylate compounds are used for a photo solder resist used as a permanent mask. As a resist material like above, there are known a novolak type epoxy acrylate compound disclosed in JP-A-61-243869, a bisphenol fluorene type epoxy acrylate compound disclosed in JP-A-3-205417 and acid-modified products of these epoxy acrylate compounds. In a use for a printed wiring board, heat resistance in an immersion into a solder bath is demanded. When the heat resistance is insufficient, swelling or peeling off of a resist film occurs, which causes defectives.
In addition to the above-mentioned heat resistance, recently, as the speed of transmission signal becomes high, a lower dielectric constant which decreases a time delay and a lower dielectric loss tangent which decreases a loss are desired for utilizing a high-frequency wave (gigahertz band). However, a conventional epoxy (meth)acrylate compound is insufficient in dielectric characteristics for coping with a high-frequency wave. For this reason, a novel epoxy (meth)acrylate compound which satisfies the above requirements is demanded.